Date:	Monday 29 June 2020
Time:	13:20 UTC
Type:	ATR 72-600 (72-212A)
Owner/operator:	Aurigny Air Services
Registration:	G-OATR
MSN:	1580
Year of manufacture:	2019
Engine model:	P&W Canada PW127
Fatalities:	Fatalities: 0 / Occupants: 56
Other fatalities:	0
Aircraft damage:	None
Category:	Serious incident
Location:	Guernsey Airport, Channel Islands (GCI/EGJB) -   United Kingdom
Phase:	Taxi
Nature:	Passenger - Scheduled
Departure airport:	Guernsey Airport, Channel Islands (GCI/EGJB)
Destination airport:	Southampton-Eastleigh Airport (SOU/EGHI)
Investigating agency:	AAIB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
An Aurigny Air Services ATR 72-600, G-OATR, was experienced smoke in the cabin following engine start at Guernsey Airport.
A similar incident occurred to ATR 72-600 G-ORAI on 22 July 2020. Both incidents were the subject of a combined AAIB Investigation, published on 13 May 2021. The following is the part of the investigation that specifically refers to G-OATR on 29 June 2020:

"Synopsis
Two separate cabin smoke events were reported while starting the engines on different aircraft in the operator’s fleet. The operator concluded that low utilisation of the aircraft and a high amount of airborne salinity resulted in corrosion forming on the P2.5/P3 engine air switching valve, sufficient to prevent it from fully closing. With the valve partially open, contaminated air from the engine was able to enter the cabin.

Safety action has been taken by the operator to help prevent corrosion forming on the valve and to amend the engine start procedure to reduce the risk of contaminated air entering the environmental control system.

History of the flight (G-OATR)
As a result of the coronavirus pandemic, the utilisation of the operator’s fleet had reduced significantly. In line with the engine manufacturer’s recommended practice for running the engines, the operator scheduled their aircraft to fly at least every 14 days. G-OATR had last flown 10 days prior to the event.

G-OATR was scheduled to fly from Guernsey Airport to Southampton Airport. The crew started both engines and the aircraft was pushed back from the stand. As the tug was being detached from the aircraft, the flight crew received a call from the Senior Cabin Crew Member (SCCM) who stated that there was a “faint haze or smoke” in the cabin. Shortly afterwards the SCCM reported that its intensity was increasing. There was no smoke or haze visible in the cockpit.

The commander turned off the cabin air recirculation fans when he was first alerted of smoke in the cabin and when he was informed that the intensity was increasing, he shut down both engines. The co-pilot reviewed the QRH for an applicable checklist, however, there was no procedure for ‘smoke on ground’. The flight crew and the SCCM agreed to rapidly disembark the passengers through the rear cabin door and a PAN call was made to ATC informing them of this decision. Once all the passengers had disembarked, the crew departed via the cabin door and liaised with the AFRS who were on scene". (G-OATR had 56 on board - 6 crew plus 50 passengers)

AAIB Conclusion
The operator determined that the smoke and haze in the cabin was due to the partial seizing of the P2.5/P3 air switching valves, which allowed oil vapour to enter the ECS. Corrosion was found in all the valves, which probably resulted from the reduced utilisation of the aircraft due to the corona virus pandemic, and the aircraft being parked and operated from an airfield close to the sea where there was a relatively high level of airborne salinity.

Safety actions
Following the events on G-OATR and G-ORAI, the following safety actions were taken:

The operator:
● Introduced a requirement for engine ground runs to be carried out on aircraft that have not flown for three days to ensure the correct operation of the bleed air system and ECS.
● Introduced an inspection of the P2.5/P3 air switching valves every 42 days and replacement of the piston ring every 100 days.
● Issued a ‘Notice to Crew’ to require flight crews and maintenance personnel to start the engines with the bleed air system and ECS selected off.

The engine manufacturer:
● Updated the EMM to include an inspection of the P2.5/P3 air switching valves following a period of storage, irrespective of duration and environment.
● Issued a requirement to replace the P2.5/P3 air switching valves during engine overhaul.
● Initiated a redesign of the P2.5/P3 air switching valve, which will consider the materials used in the valve assembly

1. AAIB Report dated 13 May 2021: https://assets.publishing.service.gov.uk/media/6076fb198fa8f5735b6602e4/ATR_72-212_A_G-OATR_and_ATR_72-212_A_G-ORAI_05-21.pdf
2. BEA France: https://bea.aero/en/investigation-reports/notified-events/detail/incident-to-an-atr-72-on-29-06-2020-at-guernsey-ad-invetigation-led-by-aaib---united-kingdom
3. Guernsey Press 17 May 2021: https://guernseypress.com/news/2021/05/17/fewer-lockdown-flights-blamed-for-incidents-of-smoke-in-aircraft-cabins/
4. https://www.itv.com/news/channel/2020-06-29/passengers-evacuated-from-smoking-aurigny-plane-in-guernsey
5. https://www.airport.gg/news/article/new-aurigny-atr-aircraft-g-oatr-arrives-guernsey
6. https://www.airfleets.net/ficheapp/plane-atr-1580.htm
7. https://en.wikipedia.org/wiki/Guernsey_Airport

G-OATR: ATR 72-600 (72-212A) of Aurigny Air Services arriving Runway 33 at Birmingham (BHX.EGBB) 17 July 2021

Date/time	Contributor	Updates
28-Oct-2024 11:22	Dr. John Smith	Added
28-Oct-2024 11:25	ASN	Updated [Narrative, Accident report, ]